If you level with friends Prot would probably be the way to go so you could pull and face tank the packs. I leveled 2 pallies both ret on beta and had 0 issues. Selfless healer and wake of ashes work absolute wonders. I leveled a bit as prot and just felt like I did 0 damage. I leveled solo so I don’t know about the xp fall off but I would assume it’s the same as legion.
The Horde 12-25 (Barrens + Stonetalon Mountains) guide has been rewritten and revamped. In addition, there has been numerous tweaks to the speedrun route to make things faster and easier to follow. Also, in case you haven't noticed I am now adding about 40% more info per step and redoing all the images. Unlike with my previous vanilla guides, I am now giving a brief explanation of where to go and what to do with each step along with any other helpful tips.
At Level 100, we recommend that you take the talent Unholy Frenzy. If you choose to take this talent over the other 2 options, then we recommend switching your Level 57 talent to Bursting Sores due to the great AoE synergy between these 2 talents. If you choose to use the talent Army of the Damned, which is an easier talent to play with, then we recommend staying with the Level 57 talent Ebon Fever.
If you already have a high level character or a friend willing to give you gold then you can purchase Heirloom items. These items are bound to account and are accessible through the Heirlooms tab using Shift+P. The benefits of these Heirloom items is that they scale with your level keeping your gear up to date without you having to worry about upgrades, and they provide a significant XP bonus.
For a new player, this will only break the immersion and spoil the 'story' of the various great storylines found throughout the game. Veteran players may want to level fast but still, revisit old places to re-experience the game through fresh eyes. How is a player to level quickly without breaking the immersion of the game? Level smart. There are ways to quickly level that apply to any area of the game.
From my understanding, the world boss is always there when your faction controls the Warfront. Like other world bosses you can only get gear from him once a week. There are other world bosses in the zones outside the warfront and 1 spawns a week just like Legion. I’m not 100% sure that the warfront will be available on launch but I have yet to read anything that says otherwise. The quest also reset once a week as well. Think of Warfronts like old Tol-Barad
Finally: Gearing happens in a pretty linear way for BFA. Once you hit 120, normal dungeons drop 310 and you need 305 item level to start heroics. Heroics drop 325 and I recommend doing Mythic at around 320. Mythic drops 340 and I highly recommend clearing every single mythic dungeon to give you the highest item level going into week 2. On launch, you will have access to 9 Mythic dungeons and there will be 1 dungeon that is gated behind honor bound rep; Siege of Boralus is gated for the Horde and King’s Rest is gated for the Alliance. I am not 100% sure on this, but I do not believe you will be able to obtain enough Honorbound rep to unlock those dungeons with the first week. Either way, its important to get a clear of all 9 dungeons first week to give you the most chances at loot. If PvP is more your thing gear starts at 280 and I am not 100 percent sure how PvP gear works for BFA. I will do more research and fill this in the best I can.
Congratulations on reaching Level 120! There are a myriad of new things to do. The first thing you should do is head to your faction hub ship where you have been doing your mission table quests and footholds to pick up and complete the quests necessary to unlock World Quests. World Quests will provide you an opportunity to grind reputation levels, acquire gear, and gather Azerite. There are tons of new things to do that we will cover in our Level 120 Battle Guide found here: Level 120 Battle Guide